Thermionic devices, such as thermionic converters, which transform input heat to electricity, are known in the art. A number of thermionic converters comprise low work function electrodes that convert heat energy to electrical energy with enhanced efficiency. Thermotunneling converters are also known to the art.
In WO99/13562 Tavkhelidze and Edelson disclose diode devices in which the separation of the electrodes is set and controlled using piezo-electric, electrostrictive, or magnetostrictive actuators. This avoids problems associated with electrode spacing changing or distorting as a result of heat stress. In addition it allows the operation of these devices at electrode separations which permit quantum electron tunneling between them. Pairs of electrodes whose surfaces replicate each other are also disclosed. These may be used in constructing devices with very close electrode spacings, including thermionic and thermotunelling converters.
In U.S. Pat. No. 6,281,514 to Tavkhelidze, a method for promoting the passage of elementary particles at or through a potential barrier comprising providing a potential barrier having a geometrical shape for causing de Broglie interference between said elementary particles is disclosed. In another embodiment, the invention provides an elementary particle-emitting surface having a series of indents. The depth of the indents is chosen so that the probability wave of the elementary particle reflected from the bottom of the indent interferes destructively with the probability wave of the elementary particle reflected from the surface. This results in the increase of tunneling through the potential barrier. When the elementary particle is an electron, then electrons tunnel through the potential barrier, thereby leading to a reduction in the effective work function of the surface. In further embodiments, the invention provides vacuum diode devices, including a vacuum diode heat pump, a thermionic converter and a photoelectric converter, in which either or both of the electrodes in these devices utilize said elementary particle-emitting surface. In yet further embodiments, the invention provides devices in which the separation of the surfaces in such devices is controlled by piezo-electric positioning elements. A further embodiment provides a method for making an elementary particle-emitting surface having a series of indents.
The internal combustion engines used in automobiles convert the expansive energy of combusted fuel into pressure and the pressure into motive power for the vehicle. This process has a number of inefficiencies. For example, it is an inefficient use of fuel, as a substantial amount of heat liberated from the fuel is wasted. Furthermore, these engines work by driving pistons up and down. This not only leads to frictional losses, but also creates unwanted vibration: many designs are expressly created to disguise these vibrations. The internal combustion engine is also noisy, and this is especially so in large vehicles such as trucks and locomotives. Moreover, the frictional forces between the components of the internal combustion engine cause considerable wear and tear on the engine, and shorten the lifetime of the vehicle and of its component parts. Further, many components of vehicles are mechanical, such as power steering, water pumping and fans.
Additionally, when a car is temporarily stopped, idling of the engine wastes energy, is inefficient and noisy, but is necessitated by the nature of internal combustion engine-driven cars.
U.S. Pat. No. 4,148,192 to Cummings discloses an internal combustion electric power hybrid power plant with a number of features. First, it allows the use of a smaller than normal internal combustion engine; the internal combustion engine is selected so as to provide sufficient power for when the vehicle is at cruising speed, and the extra torque needed for acceleration is provided by an electric motor/generator powered by a battery. Secondly, it allows energy to be conserved during braking by the motor/generator, and stored in the battery. Thirdly, one or more thermoelectric converters recover some of the energy in the waste heat from the exhaust, and this is applied to recharge the battery when the vehicle is at cruising speed. Whilst Cummings discloses that this arrangement may be used with a variety of internal combustion engines, including petrol engines, diesel engines, stratified charge engines and gas turbines, it does not overcome the major disadvantages associated with such engines, including noise, low efficiency and pollution.
U.S. Pat. No. 4,097,752 to Wolf et al. discloses an internal combustion engine in which at least one thermionic converter is acted upon by the hot exhaust gases to generate electricity, which is used to power an electric motor. Whilst Wolf et al. teach that this arrangement increases the overall efficiency of an internal combustion engine, it does not avoid the inherent disadvantages of an internal combustion engine iterated above.
U.S. Pat. No. 4,199,713 to Foster discloses an installation for supplying the electric power supply of motor vehicles that includes a generator, a battery as storage device or accumulator and several loads. A thermionic converter of conventional construction, which is operable with the fuel of the motor vehicle, is provided as generator. The electricity generated by the thermionic converter is used to power such ancillary devices as the ignition system, the injection installation, the starter, the light system, the ventilating system, the air conditioning system as well as under certain circumstances also auxiliary apparatus such as, for example, the radio, air-conditioning and the like. This arrangement generates electricity for these ancillary devices when the engine is not running, and also obviates the requirement for an alternator, with concomitant savings. This arrangement does not, however, provide enough electrical energy to propel the car via an electric motor.
Aircraft main engines not only provide thrust for flight and for taxiing but are also called upon to provide energy for running aircraft systems. This includes bleed air, hydraulic power, and electrical power. When the aircraft is on the ground, and high levels of thrust are not required, producing these ancillary services using the main engines consumes large quantities of fuel. To minimize fuel consumption and yet provide the necessary forms of power, so-called auxiliary power units or “APUs” have been deployed on many aircraft.
Demands for hydraulic power, electric power and bleed air may be and frequently are independent of one another. This means that a high demand for one or two forms of energy, say, electrical and hydraulic power, much more bleed air than is required will be generated and the system will dump or spill the excess bleed air which. In addition, gas turbine engines of the type employed in APUs operate most efficiently when operated at a constant speed, which is not necessarily consistent with the demand placed upon them.
The disadvantage of the known auxiliary power units is their relatively poor efficiency, particularly with respect to generating electricity. Their operation is also connected with high exhaust gas and noise emissions.
U.S. Pat. No. 5,235,803 to Rodgers discloses an APU that provides a dual flow, single stage centrifugal compressor by which both bleed air and turbine air may be provided. The objective was to provide, from a single stage centrifugal compressor, relatively low pressure bleed air flow to bleed air system and relatively higher pressure compressed air flow to the turbine combustor.